1. Field of the Invention
The present invention relates to refrigerator appliances, and more particularly to a self-diagnostic system for such refrigerator appliances which is capable of detecting malfunctions of the appliances and alerting the user to the occurrence of malfunctions.
2. Description of the Prior Art
Conventionally, the hitherto used diagnostically sensing and display systems for refrigerators have diagnosed the operation of operating refrigerators and alerted the user to a malfunction of the refrigerator by means of a simple display means, buzzers or other voice means upon the detection of a malfunction. However, the conventional diagnostic sensing and display systems have not had any functions for displaying the location where the malfunction occurs. Furthermore, when several malfunctions occur at the same time, they can not display and alert the user to the occurrence of all of the malfunctions at the same time. Therefore, the conventional diagnostic sensing and display systems for refrigerators must determine causes of the malfunctions of the refrigerators one by one before repairing them, which results in some difficulties and wasted time in the repairs.
U.S. Pat. No. 4,297,852 which is entitled "Refrigerator Defrost Control with Control of Time Interval Between Defrost Cycles" issued to Robert B. Brooks, Nov. 3, 1981 is a representative example of the prior art using a diagnostic sensing and display system for the refrigerator appliance. This patent discloses an automatic defrost refrigerator which is capable of controlling the time interval between defrost cycles. The control of the time interval between successive defrost cycles is carried out by delaying the normal cycling of defrost by inactivating the defrost timer until a minimum predetermined accumulated door open time is reached, starting the defrost operation of the defrost system regardless of the delaying effect of the door open measurement when the interior refrigerator temperature sensor senses an over-temperature condition indicating an abnormal build-up of frost on the evaporator coils, and providing a maximum compressor run time interval between defrost cycles when no door opening occurs, as during vacation periods.
U.S. Pat. No. 4,615,179 which is entitled "Defrost Diagnostic Arrangement for Self-Defrosting Refrigerator Appliance", issued to Norman H. Chiu et al, Oct. 7, 1986. This patent discloses a refrigerator with an apparatus for detecting a failure in an automatic defrost system which generates an "on" signal when current is sensed in the defrost heater circuit, determines the "off" time, that is the time between successive "on" signals, compares this time to a predetermined reference time longer than the normal "off" time, and signifies to the user that the defrost system is not operating properly.
The above-mentioned self-diagnostic systems for the automatic defrost refrigerators can provide good results for sensing the malfunction of the defrost system of the refrigerator and alerting the user to the occurrence of the malfunction. However, these self-diagnostic systems operate only to sense and display the malfunctions of the defrost system. As a result, they can not sense or display any malfunctions of the other functional elements of the refrigerator, which malfunctions are apt to occur.